My long-range goal is to understand the roles of extracellular matrix (ECM) molecules, particularly fibronectin (FN) and laminin (LAM), in peripheral nervous system (PNS) development. This proposal focuses on potential roles for these molecules in neural crest migration and differentiation. It is known that ECM molecules can regulate cell shape, differentiation, and movement during embryogenesis. In the PNS, the adhesive glycoproteins FN an LAM are good candidates for mediating particular stages of neural crest migration and differentiation, due to their locations in embryos and interactions with crest cells in vitro. The first specific aim is to define the effects of these molecule on differentiation of subpopulations of neural crest cells. Avian crest cells well be cultured on substrata of FN, LAM, and defined proteolytic fragments of each, and the cultures evaluated for appearance of melanocytes and neurons. Second, mechanisms of crest migration on the above substrata will be examined, using timelapse video microscopy, computer analysis, and immunostaining of cytoskeletal components. Third, the optically-clear zebrafish embryo will be used to correlate in vivo behavior of crest cells with their interactions with specific ECM components. Video microscopy, scanning electron microscopy, and immunohistochemistry will be the predominant techniques used for these studies.